The invention relates generally to the separation of gases and liquids in a fluid, and more particularly, to a gas-liquid separator that uses centrifugal force to separate the gas from the liquid while at the same time capturing one or more target substances in the fluid.
The formation of gas bubbles in the fluid of any equipment or hardware system designed to contain such fluids can significantly degrade the performance of the equipment or system. The gas bubble problem is particularly acute in low or zero-gravity environments such as in outer space where there is no gravitational force to pull the denser liquid components down and consequently force the less dense gas components up. Thus, the gas bubbles remain suspended within the fluid instead of rising to the top as would be the case in normal (1-g) gravity. For example, formation of gas bubbles have been consistently observed in space bioreactors which are cell culture vessels used to cultivate cells in space. The gas bubbles displace nutrient-rich fluids that provide nutrients for the cells and severely disrupt the flow dynamics of the fluid within the vessel. Accordingly, it is desirable to be able to remove or eliminate gas bubbles from the fluid in such bioreactor vessels.
Moreover, certain valuable bioproducts in the culture fluid flowing through the bioreactor vessel may need to be recovered and stored while other substances such as nutrients should remain in the fluid. Further, it is often necessary to store the target substances in such a way as to preserve their structural and functional integrity while staying within the limited resources and confines of spaceflight conditions. Accordingly, it is also desirable to be able to capture specific substances contained in the culture fluid and conveniently store the same while allowing other substances to pass.
One prior art method of removing gas bubbles from the bioreactor vessels involves subjecting the vessel to high-speed rotation. However, the high rotation speed may degrade the low-shear fluid dynamics of the environment in the vessel (necessary for cultivation of mammalian cells) and compromise the experiment.
Another prior art method of separating gas and liquid applies centrifugal force to the fluid to separate the heavier liquid components from the lighter gas components. Such methods typically employ a helical passageway to impart a spiraling motion to the fluid passing therethrough. The centrifugal force generated by the spiraling motion drives the heavier liquid components radially outward, separating them from the lighter gas components, which are forced toward the center of the passageway. The liquid and gas components are then discharged through different outlets. However, the fluid at the center of the passageway may still have some gas mixed therein because there is no barrier in the passageway physically preventing the liquid from mixing with the gas.
Moreover, the inventors are aware of no prior art method as yet that both removes gas from a fluid and at the same time captures certain selected substances contained in the fluid. Therefore, there exists a need for an apparatus and method of removing gas from a fluid which will preserve the low-shear environment and prevent the gas from mixing with the fluid at the boundary therebetween while at the same time capturing specific substances contained in the fluid.